Erdas 9.3 Mosaic issues
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Erdas 9.3 Mosaic issues
By elsilva in ERDAS Software Forum
Hello,
I am a new ERDAS user and I'm having some issues trying to mosaic a large number of True Color Orthophotography tiles. I have 1,776 tiles and each is 3.46MB so ~6GB of data. The computer I am using is a DELL Precision T3500 with Intel Xeon CPU, 2.67GHz, 3GB Ram running Windows XP Professional 2002, SP3.
To figure out the software/mosaic process I experimented using 10-20 tiles and it worked great but when I attempted to mosaic them all it crashed and gave me the error: Instruction at 0x00b4c335 reference memory at "0x00052888" could not be "written"
I restarted the computer to clear the memory and retried the mosaic and got the same result. Also, now every time I even open any of the tools, the tools do open but I get the error:File I/O operation failed. Only 0 of 56 bytes processed. Error no 112. There is not enough disk space.
Tips? Advice?
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Re: Erdas 9.3 Mosaic issues
By Cheryl Brantley in ERDAS Software Forum
OK. First.
Verify that your temp directory is not set to $TEMP. This directory typically does not have enough space for you temp files.
What version are you using? For 9.3 and .img output you need 2-3 times the output file size for temp space depending on what options you are using.
If you are using IMAGINE 2010, the amount of Disk Space needed varies depending on the output type. Much less space is needed now for .img
Below is a document that is located on the ERDAS Support site for users. It give you some pointers for creating better mosaicks faster.
| MosaicPro 2010 Tips & Tricks |
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| Posted 1/5/2010. MosaicPro 2010 is a high capacity, high speed, efficient image ortho-mosaic engine. It does not rely on having huge amounts of RAM, and touches the files on hard disk the fewest times possible. The robust set for radiometric adjustment, seam line editing, orthorectification, reprojection, tiling, compression and batch processing capabilities meets the needs of the production mapping industry. Yet, the user interface means this production mapping product can be used by all in the geospatial community. Beginning with the 2010 release, MosaicPro is no longer an add-on module. In ERDAS IMAGINE & LPS 2010, MosaicPro is a native part of IMAGINE Advantage and LPS Core. The 2010 version of MosaicPro represents a unification of all mosaic tools in ERDAS IMAGINE, LPS and ERDAS ER Mapper product suites. ERDAS took the best from all our eight different mosaic technologies, plus new research to release a wholly new mosaicking capability. The new capability is named MosaicPro. While it may look familiar, this is not the previous module also know as ERDAS MosaicPro, but a high capacity, high performance mosaic engine. This paper does not attempt to describe the core capabilities of the MosaicPro tool, but instead outlines the areas of improvement over the v9.3 mosaicing tools as well as providing guidelines on how best to utilize the new architecture including an explanation of such things as how temporary file space might be used during a mosaicing session so that the user can plan to have the necessary resources available to produce a successful mosaic.
Temporary File Requirements Some functions in MosaicPro must write temporary files. The number of temporary files and the size of these temporary files have been significantly reduced for MosaicPro 2010. Below is an outline of the temporary files the user can expect to see when using MosaicPro. Using all options, except exclude areas and outputting to the following file formats:
In all instances temporary files are deleted once the final mosaic file(s) have been produced and processing has ceased. Using all options, including exclude areas: For all file formats, temporary unsigned 1-bit masks are created for each image that contains the exclude areas. The temporary unsigned 1-bit mask is written using the ERDAS IMAGINE Dynamic Range Run-length Encoding (DR-RLE) .img file, so the temp space required is minimal. The amount of disk space needed is difficult to determine because there are very many variables. Nevertheless, as a guide, if you have an image of 100,000 rows x 100,000 columns which has areas to be excluded, expect the typical temporary mask to be between 6 and 12MB. An image with a lot of speckled mask areas will be bigger. The numbers of bands and bit-depth are irrelevant, because the temporary mask will be a 1-band file. Temp file locations by output mosaic file type:
Optimizing Mosaic Speed The ERDAS IMAGINE / LPS 2010 MosaicPro application is very efficient and is multi-threaded. MosaicPro touches the input pixel, data in RAM, temp files pixels, and output pixels the fewest times possible. Image blocking / tile size data performance The user can improve mosaic performance by controlling the output tile size. When the input file tile size is 64 x 64 and the output is 512 x 512, the processing engine must collect enough 64 x 64 blocks to create the 512 x 512 output block before proceeding to the next block. This disrupts the efficient data streaming and slows down the mosaicking process. You can avoid this scenario by changing your Image Files (General) and TIFF Image Files default block/tile size preferences to an output size near to the input tile size. With this in mind, you might come to the conclusion that using the same block size is always faster. This is not the case. If you have very small (input?) block sizes, say 32 x 32, outputting to a 32 x 32 block will make you touch the disk many more times than needed, slowing down the process. You would be better off using an output block of 64 x 64, and might want to run a small test on 128 x 128 to see if that would be faster on your configuration. Non blocked / tiled data performance Please expect more on this subject soon. System configuration suggestions The configuration of your system plays a very big part in the performance and scalability of MosaicPro. Below are some areas to be kept in mind. Power Consistency Many mosaicking projects take multiple hours to complete. Very large projects may take multiple days to complete. Double-check to ensure all hardware devices being used in a lengthy mosaic process are connected to a suitable Uninterrupted Power Supply (UPS). One hardware component customer typically forgets to connect to a UPS is an external Universal Serial Bus (USB) drives containing data. Limitation on File Sizes Imposed by Operating System The Microsoft Windows XP x32 operating system has a bug that will not allow the customer to create very large output files.* The maximum output file a customer can create is related to the disk blocking factor and a few other variables. Most customers can expect to create a file no larger than 30 to 35GB using this operating system. In some very rare cases, customers have been able to create files up to 200GB. Neither ERDAS not Microsoft can assist in narrowing down all the variables needing to be addressed to determine your output file maximum size. ERDAS and Microsoft suggest customers use other operating systems ERDAS IMAGINE supports to create very large files. Microsoft Windows XP x64, Microsoft Vista x32, Microsoft Vista x64, Microsoft Windows 7 x32, Microsoft Windows 7 x64, Microsoft Windows Server 2008 x32 and Microsoft Windows Server 2008 x64 do not have this problem. ERDAS has created files in excess of 2.5TB using these operating systems. Please refer to the ERDAS IMAGINE & LPS 2010 System Specifications detailed information on the service packs required for operating system support. RAM While the system specifications state the minimum RAM for ERDAS IMAGINE is 2GB, ERDAS strongly recommends using more. Multi-Core CPUs MosaicPro’s use of the multi-threading takes advantage of multiple core processors and performs very efficiently. Yet, tests indicate there is a point of diminishing returns. This point of diminishing returns is directly related to disk I/O. The mosaic process does not necessarily slow down when it reaches the diminishing return point, but the at that point the amount of performance increase no longer justifies the investment in more cores. For basic disk arrays speeds, the point of diminishing returns seems to be at eight cores. ERDAS is testing high performance disk arrays to determine if these will improve disk I/O significantly enough to move the diminishing return point beyond eight cores. Faster Disk Access ERDAS has found reading from one hard disk or hard disk array and writing to another hard disk or hard disk array has a significant impact on speed when creating very large mosaics. External USB drives are often used in mosaic processes. Reading from an external USB drive and writing to a local disk or local disk array can provide good performance. Using multiple USB drives on the same local bus will give very poor performance. This should be avoided where possible. Because network drives, arrays, whether mapped or using Universal Naming Convention (UNC) must complete with network traffic and will provide slower performance. Fast Disk Arrays Please expect more on this subject soon. * Microsoft Support Article ID 913872, “You receive error 1450 "ERROR_NO_SYSTEM_RESOURCES" when you try to create a very large file in Windows XP.” (http://support.microsoft.com/kb/913872). |
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By elsilva in ERDAS Software Forum
Hi Cheryl,
Thanks for your quick reply. I am using Imagine 9.3 and I'm not sure how to change the Temp directory? I cleared the Temp folder on the hard drive but you are talking about the application temp directory, correct? Don't know how to access that...I'm a total newbie. Thanks for your patience.
Erin
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By Cheryl Brantley in ERDAS Software Forum
You change your temp directory in your Preferences
Main Menu > Session > Preferences > User Interface and Session > halfway down you will see an entry for Temporary Directory. It is probably set to $TEMP. Change that to a large working directory if you are trying to create large output file.
Please also read information on the ERDAS support site regarding Mosaic 9.3 and large file generation. Make sure you have 9.3 fixes loaded. You can get those on the Support Site as well. You will need your company login information. Of particular note is a bug in Microsoft XP 32Bit system OS, which can limit your output to size to around 30GB, and also if you are using an external drive make sure it was not formated to FAT. (This gets a lot of users. )